Thought that some might be interested in seeing how sankyo can be applied on the ground. It came to me spontaneously while doing randori, using my legs to immobilize my partner with sankaku, and applying a sankyo for the tap. It's about 2/3rds through the video, in slow motion. Enjoy!
http://www.roydeanacademy.com/video/may_2007
Best,
Roy Dean